A. Field of the Invention
The device of the present invention generally relates to a new and improved optical transmission spectrometer for transmission measurements of scattering and absorbing samples, and more particularly, to a new and improved light beam-combiner for an optical transmission spectrometer, and a method for combining light beams from parallel sources in an optical transmission spectrometer.
B. Description of the Prior Art
Optical transmission spectrometers are commonly used to read the amount of constituents in samples such as blood samples. Typically, these instruments cannot be used to make transmission measurements of scattering sample medium. Optical transmission spectrometers can include two sources of light arranged at 90.degree. to each other. The two light sources are at different wavelengths. Performing measurements requires combining the two independent beams of light.
The typical prior art optical transmission spectrometer includes an optic known as a beamsplitter for combining the beams of light. The optic is a translucent plate mounted in the spectrometer at 45.degree. to the two incoming beams of light. In this position, the beamsplitter combines the first and second beams into a common beam directing this common beam through the specimen and onto a detector. Careful assembly of the spectrometer is required since the optic must be mounted at exactly 45.degree. to the two beams of light. Thus, precise mounting of the light sources and the optic relative to the light sources is required. A small deviation in the mounting of any of these elements results in an inoperative or inaccurate spectrometer. The optic imposes a restriction on the spectrometer since the optic can only combine two light sources, thus limiting the utility of the spectrometer in the number of tests that can be performed.
It is desirable to provide an optical transmission spectrometer that can use multiple light sources of different wavelengths allowing the instrument to conduct multiple tests on a single specimen. It is also desirable to provide a spectrometer that is small in size and uses parallel optical axes for the light sources rather than light source axes that are perpendicular to each other as in the prior art.